The present invention is directed to an improvement in a brake system which includes, in combination, a semi-metallic friction material and a braking component, the semi-metallic friction material containing metallic fiber and/or metallic powder as a main constituent. More particularly, the invention is directed to an improvement in the above-described brake system, wherein the improvement is the use of metallic fiber and/or metallic powder having a hardness lower than that of the braking component as a main constituent of the semi-metallic friction material. The use in the semi-metallic friction component of metallic fiber and/or metallic powder having a hardness lower than that of the braking component in the brake systems of automobiles, industrial machinery and railway vehicles, results in stabilization of the coefficient of friction together with lowering of the attack of the semi-metallic friction material against the brake component during braking action and suppressing of the noise generation ratio.
Generally, an FC material (cast iron) is used for the braking component in a brake system which includes a semi-metallic friction material. The hardness of it lies ordinarily within a range of Hv 170 to Hv 250, where Hv is Vickers hardness. FC is used to designate cast iron prescribed by JIS G 5501 of the Japanese Industrial Standards. Materials prescribed by JIS G 5501 correspond to those prescribed by ASTM A 48-76. The braking action made by a friction material containing steel wool and a metallic powder of a high hardness results in worsening the stability of the coefficient of friction as well as in attacking of the brake component and the generation of much noise.